Protectants, or preventative fungicides
	chlorothalonil Trade names: Bravo®, Quadris®, Echo 720®	Resistance management: Chlorothalonil is a broad-spectrum fungicide. No resistance to chlorothalonil has been reported in other crops after 35 years of use. Do not exceed a total of three applications per season, or more than 4.5 lbs active ingredient per season.
Protectants or preventative fungicides provide a barrier between the leaf and the rust spore, preventing spore germination and infection. A protective fungicide was applied in the center of this leaf. Chlorothalonil is an example of a product that is only active against spore germination. If this fungicide is applied after spores have germinated and the fungus has grown into the plant tissue, it will be totally ineffective in controlling the disease. The Strobilurin class of fungicides (azoxystrobin, pyraclostrobin, trifloxystrobin, etc) stops both spore germination and host penetration but has little or no effect once the fungus has successfully penetrated or colonized host plant tissue.	strobilurin (azoxystrobin   pyraclostrobin) Trade names: Quadris® Headline®	Resistance management: Strobilurin fungicides have a single-site mode of action, which means a single genetic change in the pathogen can cause resistance to develop. Alternating or tank-mixing between strobilurin fungicides and other labeled fungicides that have a different mode of action is essential to prevent  pathogen populations from developing resistance  developed. No more than 2 foliar applications of any strobilurin fungicide per growing season.
Curative fungicides
Curative fungicides have the ability to inhibit or stop the development of infections that are already established. With some fungicides, this includes a degree of anti-sporulant activity which helps to slow disease development by limiting the reproductive potential of the fungus. A curative fungicide was applied on the bottom leaf, but not on the upper leaves in this photo. Of the available soybean rust fungicides, only triazoles (myclobutanil, propiconazole, tebuconazole, tetraconazole, etc.) have curative activity. It is this "post infection activity" that makes triazoles the fungicide of choice if soybean rust is established at low levels in a field. If either chlorothalonil or one of the strobilurin fungicides are applied post-infection, existing infections will continue to develop. It is very important to remember that triazoles do not have unlimited curative activity. Triazole-based fungicides have reduced effectiveness once infections begin to produce spores. This is the main reason why fungicides are of little use once rust has become even moderately established in a field.	Triazoles propiconazole, tebuconazole, myclobutanil Trade names: Tilt®, Bumper®, Folicur®, Laredo, Propimax Also combined with a strobilurin fungicide: Quilt, Stratego, and Headline.	Resistance management: Plant pathogens are known to develop tolerance to triazole products used repeatedly for control. Rotate or tank mix with products with different modes of action. Do not mix or alternate with other triazole fungicides. These fungicides should be used in conjunction with disease forecasting, which recommends application timing based on environmental conditions favorable for disease development.

Possible Fungicide Interactions with Soybean Aphids and Two-Spotted Spider Mites
When considering the use of foliar fungicides, attention must be given to their ability to control the disease as well as to economics. Crop advisors must also consider their effects on entomopathic fungi. Entomopathic fungi are naturally occurring and can significantly lower arthropods populations if environmental conditions are favorable. Results from a 2005 foliar fungicide efficacy test at the West Madison Agricultural Research Station indicated a possible interaction with these fungi because some fungicide treatments had a significantly lower yield with the presence of two-spotted spider mites. Similar results are known to exist with aphids in potatoes as well as other cropping systems.